Java
Understanding JVM Memory Management
A deep dive into Java stack memory, heap memory, metaspace, and how garbage collection actually reclaims objects.
3 min read
Category
Java
21 articles
Java
Benchmarking Java Correctly with JMH
A System.nanoTime() loop around your code is not a benchmark — it's a measurement of the JIT compiler warming up. JMH exists to fix exactly that.
3 min read
Java
Generics Variance: Covariance, Wildcards, and PECS
Wildcard generics confuse most developers on sight, but the PECS rule turns a wall of question marks into a mechanical, memorable decision.
3 min read
Java
HashMap Internals: Buckets, Treeification, and Resizing
HashMap's average O(1) performance depends on assumptions about hash distribution and load factor that are worth understanding before they're violated.
3 min read
Java
String Internals: Pooling, Compact Strings, and Concatenation
Strings look like the simplest type in Java, but the string pool, compact string encoding, and concatenation strategy all affect memory and speed directly.
3 min read
Java
Hunting Memory Leaks with Heap Dumps
A Java memory leak is always a reachability bug. Heap dumps let you find exactly which reference is holding on, instead of guessing at flags.
3 min read
Java
Profiling Java Apps with async-profiler and JFR
Guessing at performance problems wastes time twice: once guessing, once confirming the guess was wrong. Here's how to actually see what the JVM is doing.
3 min read
Java
The Java Module System in Real Projects
JPMS is easy to dismiss after a rough first encounter, but used selectively it solves real encapsulation problems the classpath never could.
3 min read
Java
Optional in Java: Intended Use and Common Abuse
Optional was designed for exactly one purpose: expressive return types. Used anywhere else, it tends to add ceremony without removing any risk.
3 min read
Java
Switch Pattern Matching in Modern Java
Switch expressions with pattern matching turn instanceof chains and type-casting boilerplate into concise, exhaustive, compiler-checked logic.
3 min read
Java
A Practical Tour of java.util.concurrent
Beyond synchronized and Thread, java.util.concurrent has a purpose-built tool for nearly every coordination problem. Here's when to reach for each.
3 min read
Java
Designing Immutable Classes Properly
Marking fields final is not the same as making a class immutable. Here's what full immutability actually requires and where it usually leaks.
3 min read
Java
equals, hashCode, and the Contracts That Break Collections
A broken equals or hashCode doesn't crash your program — it quietly corrupts HashMaps and HashSets in ways that only show up much later.
3 min read
Java
ClassLoaders Demystified
ClassLoaders quietly decide how your code finds classes, why two copies of the same class can coexist, and why app servers leak metaspace.
3 min read
Java
How the JIT Compiler Actually Optimizes Your Code
The JVM doesn't run your bytecode as-is for long. Here's what C1, C2, and tiered compilation actually do, and why your benchmarks lie without warmup.
3 min read
Java
Practical Tuning Signals for G1 and ZGC
Most GC tuning advice is cargo culted flags copied from a blog post. Here's how to read the actual signals before you touch anything.
3 min read
Java
CompletableFuture Composition Patterns That Actually Work
CompletableFuture's API surface is huge and easy to misuse. These are the composition patterns that hold up in real asynchronous pipelines.
2 min read
Java
Stream API Pitfalls That Quietly Kill Performance
Streams read beautifully in code review and hide real performance costs in production. Here are the traps that show up most often and how to avoid them.
3 min read
Java
Sealed Classes and Exhaustive Pattern Matching
Sealed classes let the compiler enforce that you've handled every case, turning a class of runtime bugs into compile-time errors.
3 min read
Java
Records and Data-Oriented Programming in Java
Records aren't just less boilerplate — they push Java toward modeling data as data, separate from behavior. Here's how to use them well.
3 min read
Java
Virtual Threads in Java: What Actually Changes
Virtual threads remove the cost of blocking, not the need for careful concurrency design. Here's exactly what improves and what stays your problem.
3 min read